The present invention relates generally to what are termed shaker tables or platforms, and in particular, to a new and improved dual action shaker platform.
By the expression "shaker table" as used herein is meant the provision of a surface that may undergo a shaking motion that is useful for shaking specimens disposed upon the platform, or, in other embodiments, to shake laboratory specimens or other containers in a holder of some sort that, whether proximate or remote from the shaker table, undergoes the same motion.
Thus, in some instances, it is desired to shake specimens retained in test tubes, flasks, or the like by resting them on a table which directly holds the specimens. In other instances, the table is positioned in a certain location and attachments thereto, such as peripheral stanchions or the like, are used to support a specimen holder that may be disposed in a temperature controlled liquid bath, for example. In this instance, the table may lie beneath the housing for the bath and permit the specimens to be immersed in a bath but, by appropriately positioning the supporting stanchions so that the specimen holder is suspended from the open top of the bath, there is no need to provide fluid seal with respect to the bath contents.
Among the desired features of the satisfactory shaker apparatus are control of speed, amplitude, and, in some cases very importantly, the mode of shaking.
While various kinds of shaker tables or platforms are known to the art, there is and has been a need for an improved, mechanically simple and highly adaptable shaker platform arrangement, particularly one that could be manufactured at low cost and which is very readily convertible from one shaking mode to the other.
While various mechanical and direct drive electrical arrangements are available to impart an oscillating motion of one sort or another to a batch of specimens or the like, there has been a need for an improved shaker table which will provide either a substantially straight line or back and forth shaker motion or a true rotary shaker motion, and to be convertible between these modes of operation by a simple, foolproof manipulation.
There has also been a need for a shaker platform drive arrangement wherein the shaker mechanism is readily adjustable both as to stroke length and to mode of operation, and is furthermore adaptable to positioning a load carrier in a variety of ways without changing the underlying part of the apparatus. There is further need in the laboratory or scientific community for an apparatus which is constructed and arranged so that the load bearing parts will be durable in use and hence provide long-term economy.
In view of the failure of the prior art to provide a dual mode shaker table or platform of optimum design, it is an object of the present invention to provide an improved shaker table arrangement.
Another object of the invention is to provide a shaker platform arrangement that may support a load directly or somewhat indirectly, depending on the desired application.
Still another object of the invention is to provide an apparatus wherein shifting or converting the apparatus from the reciprocating cycle to a rotary cycle is capable of being carried out with a change to only a single part or element.
A further object of the invention is to provide a shaker platform arrangement having a drive mechanism which is equally effective regardless of stroke length.
A still further object of the invention is to provide a shaker platform that is able to be controlled in respect to three variables and which is free from maintenance-intensive elements and which is comparatively simple and reliable in use.
Yet another object of the invention is to provide a shaker table or platform in which the vertical load imposed by the components and the live load or articles to be shaken is taken by elements that are independent of the elements supplying the shaking motion.
Another object of the invention is to provide a shaker table mechanism wherein two sets of parallelogram linkages are present, one linkage including a pair of links mounted to a base and also to one portion of an intermediate or idler member forming a fourth link, and wherein the second linkage comprises links attached to another part of the intermediate or idler member and also to the table, with one set of links permitting motion in one direction and the second set of links permitting motion in a second, perpendicular direction, with the actual motion being determined by the form connection between the table and a rotary crank pin, or between the table and another link element.
An additional object of the invention is to provide two sets of parallelogram linkages in a shaker table, with a first set of links pivoting relative to the unit base and the other set of links pivoting with respect to a plate or L-member carried by the first set of links, and with a drive link and one of the second links each including an extension which may be removably secured to a portion of the table to determine the shaking mode desired.
Yet another object of the invention is to provide a shaker table of the type described herein wherein the stroke length adjustment is readily made by swinging the crank pin carrier through an arc relative to the center line of the drive element to obtain an increased or decreased stroke length of the crank pin.
According to the invention, an arrangement of links and plates is provided to permit the choice of a primarily reciprocating or a rotating motion of the shaker table. The table is supported at plural, spaced apart points by universal joints or the like permitting free but limited movement of the table under the influence of the drive mechanism. The drive mechanism includes a motor and a rotary element having a crank pin affixed thereto and optionally arranged so as to permit variation in the stroke of the crank pin.
An important feature of the invention is that the type of motion transmitted by the drive link to the table is determined by the manner in which a portion of one link or the other is secured to the table. In one mode, the drive link is not only rigid in itself, but is attached to the table at two points along its length. Accordingly, with the drive connection being affixed to the crank pin, the table will replicate the rotary motion of the crank pin. In this mode, the links permit such two-axis motion without allowing the table to turn about its own axis.
In the other mode of operation, the drive link is pivotally connected to both the crank pin and the table, allowing its free end (the end opposite the crank pin end) of the drive link to swing freely. In this mode, the second set of links cannot pivot relative to the table, but the first set of links allows a reciprocating motion along an axis determined by the location of the fixed pivots for the links.
The invention achieves its objects and advantages and other inherent objects and advantages by providing a base unit, a shaker table supported on the base unit, a motor drive arrangement including a rotary crank pin and a drive link with one end attachable to the crank pin, an opposite end fixable to the table and a center portion pivotally attached to the table, first and second sets of parallelogram-forming links, the first set permitting movement parallel to a first line or locus and the second set permitting movement parallel to a second locus perpendicular to the first line, and an auxiliary mechanism for selectively connecting the table to the drive link at either the opposite end of the drive link or an extension of one of the second pair of links. The objects are also achieved by providing an apparatus of the type just described that includes preferred forms of table support, stroke length adjustment and variation of shaker speed to provide improved versatility and reliability in use.
The exact manner in which the foregoing and other objects and advantages of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiment of the invention set forth by way of example and shown in the accompanying drawings in which like reference numbers indicate corresponding parts throughout.